configs: sm6150: support a2dp echo reference for sound trigger

Add a2dp echo reference mixer controls for SVA.

Change-Id: If5d1610ff0193682aa96ffee5e3887e185e6c620
diff --git a/configs/msmsteppe/sound_trigger_mixer_paths.xml b/configs/msmsteppe/sound_trigger_mixer_paths.xml
index bd114de..09fc064 100644
--- a/configs/msmsteppe/sound_trigger_mixer_paths.xml
+++ b/configs/msmsteppe/sound_trigger_mixer_paths.xml
@@ -202,5 +202,11 @@
         <ctl name="EC Reference SampleRate" value="48000"/>
     </path>
 
+    <path name="echo-reference a2dp">
+        <ctl name="AUDIO_REF_EC_UL1 MUX" value="SLIM_7_RX"/>
+        <ctl name="EC Reference Channels" value="Two"/>
+        <ctl name="EC Reference Bit Format" value="S16_LE"/>
+        <ctl name="EC Reference SampleRate" value="48000"/>
+    </path>
 
 </mixer>